<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        @media ( width:320px ) {
            html { font-size:  32px; }
        }
        @media ( width:375px ) {
            html {
                font-size: 37.5px;
            }
        }
        @media ( width:414px) {
            html { font-size: 41.4px; }
        }
        * {
            margin: 0;
            padding: 0;
        }
        div {
            width: 5rem;
            height: 3rem;
            background-color: pink;
        }
    </style>
</head>
<body>
    <div></div>
</body>
</html>